babel-plugin-react-transform

This plugin wraps React components with arbitrary transforms. In other words, it allows you to instrument React components in any way—limited only by your imagination.

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This is highly experimental tech. If you’re enthusiastic about hot reloading, by all means, give it a try, but don’t bet your project on it. Either of the technologies it relies upon may change drastically or get deprecated any day. You’ve been warned 😉 .

This technology exists to prototype next-generation React developer experience. Please don’t use it blindly if you don’t know the underlying technologies well. Otherwise you are likely to get disillusioned with JavaScript tooling.

No effort went into making this user-friendly yet. The goal is to eventually kill this technology in favor of less hacky technologies baked into React. These projects are not long term.

Demo Project

Installation

This plugin is designed to be used with the Babel 6 ecosystem. These instructions assume you have a working project set up. If you do not have Babel set up in your project, learn how to integrate it with your toolkit before installing this plugin.

Configuration

Add react-transform to the list of plugins in your babel configuration (usually .babelrc):

{
"presets": ["react", "es2015"],
"env": {
// this plugin will be included only in development mode, e.g.// if NODE_ENV (or BABEL_ENV) environment variable is not set// or is equal to "development""development": {
"plugins": [
// must be an array with options object as second item
["react-transform", {
// must be an array of objects"transforms": [{
// can be an NPM module name or a local path"transform":"react-transform-hmr",
// see transform docs for "imports" and "locals" dependencies"imports": ["react"],
"locals": ["module"]
}, {
// you can have many transforms, not just one"transform":"react-transform-catch-errors",
"imports": ["react", "redbox-react"]
}, {
// can be an NPM module name or a local path"transform":"./src/my-custom-transform"
}]
// by default we only look for `React.createClass` (and ES6 classes)// but you can tell the plugin to look for different component factories:// factoryMethods: ["React.createClass", "createClass"]
}]
]
}
}
}

As you can see, each transform, apart from the transform field where you write it name, also has imports and locals fields. You should consult the docs of each individual transform to learn which imports and locals it might need, and how it uses them. You probably already guessed that this is just a way to inject local variables (like module) or dependencies (like react) into the transforms that need them.

You may optionally specify an array of strings called factoryMethods if you want the plugin to look for components created with a factory method other than React.createClass. Note that you don’t have to do anything special to look for ES6 components—factoryMethods is only relevant if you use factory methods akin to React.createClass.

Writing Transforms

It’s not hard to write a custom transform! First, make sure you call your NPM package react-transform-* so we have uniform naming across the transforms. The only thing you should export from your transform module is a function.

As you can see, you’ll receive ReactClass as a parameter. It’s up to you to do something with it: monkeypatch its methods, create another component with the same prototype and a few different methods, wrap it into a higher-order component, etc. Be creative!

Of course, you might not want to use all options, but isn’t it nice to know that you have access to them in the top scope—which means before the component definitions actually run? (Hint: a hot reloading plugin might use this to decide whether a module is worthy of reloading, even if it contains an error and no React components have yet been wrapped because of it.)

So, to retrieve the displayName (or isInFunction, when available), use the options parameter and the second uniqueId parameter given to the inner function after ReactClass:

Sure, it’s a slightly contrived example, as you can grab ReactClass.displayName just fine, but it illustrates a point: you have information about all of the components inside a file before that file executes, which is very handy for some transformations.